EF4 Tornado — Grady, Oklahoma

2011-05-24 · near Norge, Grady, Oklahoma

Event narrative

This tornado is labeled C1 (Segment #1 of the Chickasha-Blanchard-Newcastle tornado). The tornado formed on the south side of Chickasha, quickly doing EF-2 damage. Mobile homes were damaged and destroyed, trees were uprooted/destroyed, outbuildings were destroyed, and many buildings lost significant portions of their roofs. One fatality occurred as a mobile home was destroyed in the south portion of Chickasha. As the tornado moved northeast of Chickasha, it gained significant strength, with several areas receiving EF-4 damage. Well-built homes were destroyed. Trees were debarked with only stumps remaining. Cars were thrown hundreds of feet. Almost continuous EF-3/occasional EF-4 damage occurred northeast until it crossed into McClain county 1.5 miles south of Highway 9. The tornado was probably at its strongest as it neared/crossed the McClain county line. Wind speeds there were estimated near 200 mph. Monetary damage estimates were not available.

Wider weather episode

A tornado outbreak occurred over parts of northern and central Oklahoma during the day on the 24th, with violent tornadoes devastating several communities. By the end of the day, one EF-5, two EF-4, and two EF-3 tornadoes destroyed buildings, ripped up trees and power poles, and unfortunately, resulted in 11 deaths. The day began with a strong upper level trough ejecting out of the southwest United States. The trough took on a negative tilt as it approached the southern Plains. A strong jet stream was located at both the middle and upper levels rotating around the upper trough. At the surface, a low pressure strengthened rapidly over northwest Oklahoma, keeping the low-level flow of warm, moist air to flow east of a dry line that had moved into western Oklahoma. Thunderstorms developed by early afternoon over western Oklahoma, and quickly became supercellular as they moved northeast. Strong low-level rotation developed early, with the first tornado occurring over Blaine county, and moved northeast into Major county. Another supercell rapidly gained low-level rotation as it moved from Caddo into Canadian County. This tornado became the strongest of them all as it moved north of El Reno, west of Piedmont, and to south of Guthrie in Logan county. Nine people died as a result of this tornado. Two more powerful supercells developed over Grady county, and they moved northeast into McClain and Cleveland counties. Finally, the final tornado occurred east of Norman into Pottawatomie county. The timing of this outbreak could not have come at a worse time, as rush hour was just unfolding as the tornadoes neared the Oklahoma City metro area.

View location on OpenStreetMap → (35.0080, -97.9610)

Source: NOAA Storm Events Database, event_id 315858. Narrative written by the NWS forecast office that issued the report.